5.09 Schizophrenia

Psychiatry review for the USMLE Step 1 Exam

• Epidemiology:
  • Slight male predilection (1.4:1 male to female ratio).
  • Men present between 18-25, women between 28-35.
  • Affects about 0.5% of the population.
• Symptoms:
  • Positive symptoms: hallucinations, delusions, disorganized behavior and speech.
  • Negative symptoms: flat affect, anhedonia, apathy, alogia, lack of interest in socialization.
  • Cognitive symptoms: impairments in attention, executive function, working memory.
• Diagnosis:
  • Criteria: two or more symptoms lasting over a month.
  • Schizophreniform disorder if symptoms last less than 1 month.
• Pathophysiology:
  • Excess dopamine in prefrontal cortical pathway (negative symptoms).
  • Excess dopamine in mesolimbic pathway (positive symptoms).
  • Other neurotransmitters may also play a role (especially serotonin excess).
• Treatments:
  • Antipsychotics (D2 receptor antagonists).
  • First-generation antipsychotics: haloperidol, chlorpromazine (more side effects).
  • Second-generation antipsychotics (atypical antipsychotics): aripiprazole, olanzapine, quetiapine, risperidone (lower extrapyramidal side effects, higher metabolic side effects).
• Outcomes:
  • Rule of thirds: one-third full recovery, one-third improved with mild symptoms, one-third require high-level care.